In general, work machines include machines and vehicles for performing various types of works (hereinafter, referred to as work machines), for example, a civil engineering/construction machine such as a hydraulic shovel and the like, an agriculture machine such as a tractor and the like, a material handling machine, and other industrial machines, vehicles and the like. An operator's cab disposed to these work machines is placed in a bad working environment with violent noise and vibration.
For example, there is a hydraulic shovel 100 as one of civil engineering/construction machines as shown in FIG. 8. In the hydraulic shovel 100, an upper pivot body 103 is pivotably disposed on a lower traveling body 101 through a pivot mechanism 102. The upper pivot body 103 is provided with power units such as a work machine 104, an engine 108 and the like, and an operator's cab 110, and the like. Further, in general, this type of the work machine 104 has an attachment 107 attached thereto such as a boom 105 disposed to perform an up and down operation, an arm 106 mounted at an extreme end of the boom 105 to pivot up and down, a bucket disposed at an extreme end of the arm 106, and the like.
The operator's cab 110 is ordinarily formed in a box shape, and has a front window attached to a front surface and a window formed on a rear portion in a size as large as possible. Further, the operator's cab 110 is also provided with a window in an upper half portion on a side where the work machine 104 is installed (on a right side in a traveling direction of the vehicle) as shown in FIG. 8, and a door 111 is disposed to an opposite side of the window (on a left side in the traveling direction of the vehicle). An operator enters and exits the operator's cab 110 by opening and closing the door 111.
In the hydraulic shovel 100, drive machines such as a vehicle-mounted engine 108 and the like are disposed rearward of the operator's cab 110. In addition, the work machine 104 disposed forward of the operator's cab 110 performs work such as excavation, lifting of soil, and the like. As a result, an inside of the operator's cab 110, in which the operator drives the hydraulic shovel, has violent noise and vibration and is placed in a very bad working environment. For this reason, there is conventionally required to improve dwelling comfort in the operator's cab by suppressing noise to the operator's cab 110 in order to improve a working environment of the operator.
In contrast, for example, a passenger car is provided with noise insulation means for preventing noise from an engine into a compartment. As the noise insulation means, an action of bonding a noise insulation material to partition parts, and the like is ordinarily employed. As a method of attaching the noise insulation material, Japanese Patent Application Laid-Open No. 2003-10967 (patent document 1) discloses a method of manufacturing noise insulating body parts. In the method of manufacturing the noise insulating body parts, in order to fill body parts such as a dash lower with a noise insulation material, a noise insulation material is previously inserted into a molded vehicle part before it is foamed, the inserted noise insulation material is partly foamed by heat when the vehicle part is welded, and then the overall noise insulation material is heated and foamed. Further, a plurality of ribs are disposed in a row in the dash lower along an extending direction thereof so that they act as fitting means and reinforcing means of the noise insulation material.
Further, for example, Japanese Patent No. 3280845 (patent document 2) proposes an interior material for a passenger car. In the interior material for the passenger car, a plurality of fan-shaped continuous reinforcing ribs are disposed in contact with an inner surface of the interior material that covers a space formed adjacent to a structure member such as a pillar panel, a side roof and the like of the passenger car as well as additional ribs smaller than the reinforcing ribs interposed between the reinforcing ribs as means for preventing noise such as a zoom generated when the passenger car travels.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-10967
Patent Document 2: Japanese Patent No. 3280845